1. Field of the Invention
The present invention relates to a vibrating alert device including a built-in motor such as for a mobile phone, more particularly relates to a technique for controlling the strength of the vibration.
2. Description of the Related Art
Mobile phones often include built-in intermittent vibration controllers which supply power source voltage intermittently to a vibrating motor for the duration of an incoming call signal. The vibrating motor repeatedly operates to vibrate for exactly a constant time from the incoming call by a constant strength (constant rotational speed of the motor), then stop vibrating for exactly a predetermined time, that is, operates in an intermittent constant vibration control mode.
There is however a problem in the above intermittent constant vibration control mode. That is, the degree to which a user of a phone senses vibration of the vibrating motor differs depending on the user or on the position the phone is carried or stored at. Therefore, some users will sense the vibration too strongly and be overly startled and will therefore find the vibration distasteful, while others will feel it only weakly and find the effectiveness of the alert insufficient.
An object of the present invention is to provide a vibrating alert device improving the vibration control mode so as not to startle the user by the vibration and to improve the effectiveness of the alert.
To attain the above object, there is provided a vibrating alert device including a built-in vibrating motor, provided with a vibration strength control means becoming active over a duration of a vibration control signal and repeatedly operating to increase a drive voltage supplied to the vibrating motor in stages from a minimum vibration strength voltage to a maximum vibration strength voltage.
Preferably, the incrementally increasing means includes a voltage generating means for generating vibration strength voltages from the minimum vibration strength voltage to the maximum vibration strength voltage based on a power source voltage and a voltage selecting means for selecting and outputting in a rising order the vibration strength voltages.
More preferably, the voltage selecting means interposes and outputs a non-vibration strength voltage for exactly a predetermined time before selecting the second and later vibration strength voltages.
Still more preferably, the voltage selecting means interposes and outputs a non-vibration strength voltage for exactly a predetermined time after selecting the maximum vibration strength voltage and before selecting the minimum vibration strength voltage.